Why collect rainwater on your property?
As Auckland’s population grows, more development takes place.
Rainfall that used to infiltrate through the soils, or slowly drain overland, runs much faster across sealed surfaces, and into the piped stormwater network.
This will continue to increase as the city grows and climate change creates more extreme rainfall events.
Benefits of collecting rainwater
Collecting rainwater enables you to remove rainfall from the stormwater system by storing it for later use on your property and/or detaining it for slow release back into the network.
Collecting rainwater enables you to:
- make use of a readily available natural resource
- generate your own water supply should there be a water restriction or in times of an emergency
- saves money on your water bill by using roof-collected rainwater to water the garden, wash the car or flush the toilet.
Rainwater collection can also help reduce the negative effects that stormwater has on the environment.
Do I need a rainwater tank as part of a new development?
If you are replacing natural ground with sealed surfaces, in either a new build or the development of an existing property, you may be required to manage the additional stormwater runoff generated.
A rainwater tank is one way to do this.
See the Auckland Design Manual website for more information on stormwater management devices.
Types of water tanks
Rainwater tanks come in different shapes and sizes.
They can also be made from varying materials including plastic, concrete or metal.
If you are already connected to the centralised water network and are short of space, slim-line tanks are a good option. They can fit along the side of your house, fence, or garage.
Bladder tanks are designed to fit under floors and decks, making use of previously unused space.
Retention tanks retain water for future use.
|Non-potable (non-drinking water)||Outdoor use, such as washing a car or watering garden||Non-potable (single use) retention tank or rain barrel|
Outdoor use, toilet flushing and laundry use
Non-potable (single use) retention tank
|Potable water (full drinking water supply)|
Outdoor and indoor uses, including kitchen and bathroom water supply. Water must be purified.
Most suitable for households NOT connected to the centralised water network.
|Potable (or complete supply) water retention tank|
Detention tanks capture rainwater and store it, slowly releasing it back to the stormwater network.
This contributes to reducing the flow of stormwater runoff and minimises the negative effects on the environment, such as bank erosion, sewer and stormwater overflows.
A detention function can be added to a retention tank to make it a dual purpose system.
Health considerations with using rainwater tanks
If you are using water from a rainwater collection tank, you must ensure the quality of it is safe and fit for its intended use, for example outdoor use only or potable water supply.
You can lessen health risks by:
- using a registered plumber to install your tank
- ensuring your roof and gutters are clean
- using filters, mesh guards and a backflow prevention device
- clearly labelling rainwater tanks to indicate the water is not for drinking.
Non-potable (non-drinkable) rainwater tank water should not be consumed unless there is a need for emergency supply. In this case, boil the water before use and follow Ministry of Health guidelines.
For more information on rainwater tank maintenance, see the operation and maintenance manual that came with your tank, or read our guidance document for on-site stormwater tanks.